The value of plasma paraquat concentration in predicting therapeutic effects of haemoperfusion in patients with acute paraquat poisoning.

Objective: This study was aimed to analyze the scavenging effect of haemoperfusion on plasma paraquat (PQ) and to evaluate the clinical significance of PQ examination in the treatment of patients with acute paraquat poisoning.

Methods: 85 patients with acute paraquat intoxication by oral ingestion were admitted in West China Hospital from Jun, 2010 to Mar, 2011. A standardized therapeutic regimen including emergency haemoperfusion was given on all subjects. A total of 91 whole blood samples were taken before (0 h), underway (1 h after haemoperfusion beginning) and at the end (2 h) of the haemoperfusion therapy. The clearance rate was calculated and related factors were analyzed.

Results: As heamoperfusion was going on, the plasma paraquat concentration of the patients kept falling down. After 1 hour of haemoperfusion, the average clearance rate (R(1)) was 37.06±21.81%. After 2 hours of haemoperfusion, the average clearance rate (R(2)) was 45.99±23.13%. The average of R(1)/R(2) ratio was 76.61±22.80%. In the high paraquat concentration group (plasma paraquat concentration (C(0)) >300 ng/mL), both the averages of R(1) and R(2) were significantly higher than those of the low paraquat concentration group (C(0)≤200 ng/mL) (p<0.05), and there was no significant difference of R(1)/R(2) between these two groups (p>0.05).

Conclusions: The dynamic monitoring of plasma PQ concentration was not only critical in the clinical evaluation but also helpful in guiding the treatment of patients with acute PQ intoxication. Haemoperfusion can effectively eliminate paraquat from the plasma in patients with high initial plasma PQ concentration, while in patients with low initial plasma PQ concentration (<200 ng/ml), the clearance effect of harmoperfusion was very limited. Increasing HP time might improve the overall clearance rate of HP on plasma PQ yet decrease the elimination efficiency of HP, while repeated HP treatment was helpful against the rebound phenomena.